This invention relates to apparatus for removing rocker arms in a cam-activated valve mechanism of an engine. The tool also can be used to remove the valve springs of the valve mechanism in preparation for removing the valves.
The job of overhauling an automobile engine is time-consuming and costly to the automobile owner. The job of disassembling and reassembling certain automobile engines is especially tedious and time-consuming when there are no tools available to aid the repairman in accomplishing certain necessary steps in the repair process. For example, to remove the valves in an overhead cam engine manufactured by Nissan Motor Company, Ltd., Tokyo, Japan (Datsun), or other similar engines, the cam shaft sprocket is removed to free the timing chain. The sprocket is removed so that the cylinder head can be removed from the engine block. The rocker arm cover is removed to expose the top of the valve mechanism. The valve system has pivot-type rocker arms which are activated directly by rotation of the cam shaft. To remove the valves, the rocker arms and valve springs are initially removed to free the valves for removal. To remove the rocker arms, each valve spring engaged with the rocker arm first must be compressed so the rocker arm can be slipped out of engagement with the valve rocker guide and the cam shaft.
It is common for repairmen to compress the valve springs with a screwdriver or other similar tool. The tip of the screwdriver is applied to the top of the valve spring and the opposite end of the screwdriver is then forced toward the body of the cam shaft to apply pressure to the side of the cam shaft, using the cam shaft as a fulcrum to apply downward pressure on the spring with the tip of the screwdriver. The use of a screwdriver in this way to compress the valve springs has been a recommended procedure in a service manual published by an automobile manufacturer.
The use of the cam shaft body as a pressure point for applying sufficient force to depress the valve springs can have serious consequences. A cam shaft is made from cast iron and is relatively ductile. A tool forced against the cam shaft can score the cam shaft which can weaken it or even lead to fracturing of the cam shaft during use.
The present invention provides apparatus for removing rocker arms in which the valve springs can be compressed without contacting the cam shaft or any other critical moving part of the automobile engine. The apparatus of this invention also facilitates quick and easy removal of the rocker arms as well as the valve springs, and can provide a substantial saving of time required to remove and replace the valves, valve springs and rocker arms.